MAX16046A Datasheet, PDF (30/71 Pages) Maxim Integrated Products – 12-Channel/8-Channel EEPROM-Programmable System Managers with Nonvolatile Fault Registers

12-Channel/8-Channel EEPROM-Programmable
System Managers with Nonvolatile Fault Registers
MAX16046A fig03
MAX16046A fig04
V_CC
2V/div
0V
RESET
2V/div
0V
EN_OUT_
2V/div
0V
UVLO
HIGH-Z
ASSERTED
LOW
V_CC
2V/div
0V
RESET
2V/div
0V
EN_OUT_
2V/div
0V
20ms/div
Figure 3. RESET and EN_OUT_ During Power-Up, EN_OUT_ Is
in Open-Drain Active-Low Configuration
Sequencing
Each EN_OUT_ has one or more associated MON_
inputs, facilitating the voltage monitoring of multiple
power supplies. To sequence a system of power sup-
plies safely, the output voltage of a power supply must
be good before the next power supply may turn on.
Connect EN_OUT_ outputs to the enable input of an
external power supply and connect MON_ inputs to the
output of the power supply for voltage monitoring. More
than one MON_ may be used if the power supply has
multiple outputs.
Sequence Order
The MAX16046A/MAX16048A utilize a system of
ordered slots to sequence multiple power supplies. To
determine the sequence order, assign each EN_OUT_
to a slot ranging from Slot 0 to Slot 11. EN_OUT_(s)
assigned to Slot 0 are turned on first, followed by out-
puts assigned to Slot 1, and so on through Slot 11.
Multiple EN_OUT_s assigned to the same slot turn on at
the same time.
Each slot has a built-in configurable sequence delay
(registers r50h to r54h) ranging from 20μs to 2.4s.
During a reverse sequence, slots are turned off in
reverse order starting from Slot 11. The MAX16046A/
MAX16048A may be configured to power-down in
simultaneous mode or in reverse sequence mode as
set in r54h[4]. See Tables 10, 11, and 12 for the
EN_OUT_ slot assignment bits, and Tables 13 and 14
for the sequence delays.
Monitoring Inputs While Sequencing
An enabled MON_ input may be assigned to a slot rang-
ing from Slot 1 to Slot 12. Monitoring inputs are always
checked at the beginning of a slot. The inputs are given
the power-up fault delay within which they must satisfy
10ms/div
Figure 4. RESET and EN_OUT_ During Power-Up, EN_OUT_ Is
in Push-Pull Active-High Configuration
the programmed undervoltage limit; otherwise a fault
condition will occur. The fault occurs regardless of the
critical fault enable bits. This undervoltage limit cannot
be disabled during power-up and power-down.
EN_OUT_s configured for open-drain, push-pull, or
charge-pump operation are always asserted at the end
of a slot, following the sequence delay. See Tables 10,
11, and 12 for the MON_ slot assignment bits.
Slot 0 does not monitor any MON_ input. Instead, Slot 0
waits for the Software Enable bit r4Dh[0] to be a logic
‘0’ and for the voltage on EN to rise above 0.525V
before asserting any assigned outputs. Outputs
assigned to Slot 0 are asserted before the Slot 0
sequence delay. Generally, Slot 0 controls the enable
inputs of power supplies that are first in the sequence.
Similarly, Slot 12 does not control any EN_OUT_ outputs.
Rather, Slot 12 monitors assigned MON_ inputs and then
enters the power-on state. Generally, Slot 12 monitors
the last power supplies in the sequence. The power-up
sequence is complete when any MON_ inputs assigned
to Slot 12 exceed their undervoltage thresholds and the
sequence delay is expired. If no MON_ inputs are
assigned to Slot 12, the power-up sequence is complete
after the slot sequence delay is expired.
The output rail(s) of a power supply should be monitored
by one or more MON_ inputs placed in the succeeding
slot, ensuring that the output of the supply is not checked
until it has first been turned on. For example, if a power
supply uses EN_OUT1 located in Slot 3 and has two
monitoring inputs, MON1 and MON2, they must both be
assigned to Slot 4. In this example, EN_OUT1 turns on at
the end of Slot 3. At the start of Slot 4, MON1 and MON2
must exceed the undervoltage threshold before the pro-
grammed power-up fault delay; otherwise a fault triggers.
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